He studied mechanical engineering at UCLA where he was a member of the Phi Delta Theta Fraternity. He was forced to drop out when the Great Depression of the late 1920s hit and soon began work at various family businesses including a pool hall, a hot dog stand, shooting gallery and a bingo-style operation called the "Reno Game".

Bingo was illegal in California, but games of skill based on bingo were legal. The Reno or Circle Game involved rolling a ball down a board where it would register a card suit and number. If one of the 33 players seated in a circle around the board matched a four-card sequence, he or she won, unless they were a shill, working for the house. The use of shills to fill the games upset players, but John Harrah felt they were necessary.

The Reno Game was shut down several times by local authorities, but each time, lawyer John Harrah would get his permit reinstated. Still, the cost of doing business was high. When twenty-year-old Bill told his father he should get rid of the shills and put more money into the business, John challenged him to run the operation by himself. Bill said, "Dad, that would suit me just fine," and paid his father $500 for the business. He then headed down to the pier and fired the shills.

In the course of just three years Harrah made the $100-a-week game into a $25,000 per year business. However, Bill grew tired of fighting the politicians and wanted to expand his operations into Reno. On October 29, 1937, he opened his first club at 124 North Center Street, called Harrah's Club Bingo. The location was two blocks from the Bank Club and Palace Club that dominated gaming in Reno.

As the locals expected, his tiny tango (bingo) parlor closed-up fast, lasting only until November the 15th.[1] In July 1938 Bill opened another bingo parlor, this time closer to the action, called Harrah's Plaza Tango. Virgil Smith was the main financier and a partner in the operation, and also in the club that opened in 1938, called the Plaza Tango at 14 East Commercial Row. Two months later Harrah found a better location at 242 North Virginia Street, close to Harolds Club, called Ed Howe's Tango Club.

After a sit-down with Nick Abelman, Bill Graham, and Jim McKay, Harrah waited to be accepted into the Reno gaming fraternity. Eventually, Cal Custer, a respected ex-bootlegger and a long-time confidant of John Harrah, stood up for Bill. His new business ventures were given the green light, after a cash payment was made.

Ed Howe wanted $25,000 for his Tango Club, but accepted just $1,000 from Harrah now that he was a part of Bill Graham's group. Over time, Harrah tried other locations and expanded his casino on Virginia Street several times. A hotel tower opened in 1969.

At Lake Tahoe, Harrah purchased George's Gateway Club in 1955 to expanded his empire. Harrah-owned properties included the Lake Club on the lake side of highway 50, Harrah's Tahoe, on the mountain side at the old Stateline Country Club. The hotel tower opened in 1973. Harrah also owned the Zephyr Cove restaurant past Cave Rock which offered slots and blackjack.

Harrah expanded to Las Vegas in 1973 by purchasing the Holiday Casino on the Las Vegas Strip from Shelby and Claudine Williams. The property was close to the successful Sands Casino and across from where the Mirage now stands.

Harrah trusted his top executives, and while he spent time walking his properties and demanding that things were perfect, he delegated authority and his managers appreciated his trust in their ability to manage his properties.

Harrah used his influence to create the Nevada Gaming Control Board in 1955, an organization designed to regulate gaming in Nevada. In 1959, Harrah helped create an even stronger Gaming Commission to rid the state's casinos of corruption.

Harrah was known for his relations with both his customers and employees.[2] He was the first to invite African-American entertainers to perform in his casinos and welcome all races.[citation needed] He removed the color and sexual barrier by hiring women as dealers as well as other employees regardless of skin color or gender.[citation needed] The main theater in Harrah's Reno was named Sammy's Showroom after entertainer Sammy Davis, Jr. (whose Duesenberg replica now resides in the museum that bears Harrah's name),[3] and actor-comedian Bill Cosby recalls Harrah as a good friend.[4]

Harrah had an extensive collection of cars. Many of his cars enjoyed 'best' or 'one-of-a kind' status. Some notable mentions in his collection were the two Bugatti Type 41s, a Phantom Corsair, two Ferraris among several others. In 1966 his 1931 Bugatti Type 41 Coupe de Ville won Best of Show at Pebble Beach. After his death Holiday Inn acquired Harrah's of which the car collection was part of. The bulk of the collection were sold at several auctions between 1984-1986 for more than $100 million. An outcry by the people of Reno and Sparks led to Holiday Inn donating 175 vehicles to establish the National Automobile Museum in Reno, Nevada, a collection also referred to as The Harrah Collection. Some cars were also donated to form the Imperial Palace Auto Collection in Las Vegas.

Harrah was married seven times to six women, including the singer-songwriter Bobbie Gentry in 1969. With ex-wife Scherry (whom he married twice), he adopted two boys named John and Tony.[5] His widow, Verna, worked as a film producer on such features as Anaconda. The highest Total Rewards Card Tier, "Seven Stars", was named after his seven wives.